Clustering of mutations in the biotin-binding region of holocarboxylase synthetase in biotin-responsive multiple carboxylase deficiency

Holocarboxylase synthetase (HCS) catalyses the biotinylation of the four biotin-dependent carboxylases found in humans. A deficiency in HCS results in biotin-responsive multiple carboxylase deficiency (MCD). We have identified six different point mutations in the HCS gene in nine patients with MCD. Two of the mutations are frequent among the MCD patients analyzed. Four of the mutations cluster in the putative biotin- binding domain as deduced from the corresponding Escherichia coli enzyme and consistent with an explanation for biotin-responsiveness based on altered affinity for biotin. The two others may define an additional domain involved in biotin-binding or biotin-mediated stabilization of the protein.      

Leiomyosarcoma of the inferior vena cava: analysis and search of world literature on 141 patients and report of three new cases

Leiomyosarcoma of the inferior vena cava is a rare and potentially curable tumor. Uncertainty about the results of treatment derives from lack of a large series in the same center and of a long-term follow-up of the published cases. A review of the world literature from 1871 to 1989 allowed us to collect information on 141 patients with inferior vena cava leiomyosarcoma to which our three cases have to be added. The tumor arose from the lower segment of the inferior vena cava (infrarenal portion) in 49 patients, from the middle segment (from the renal veins to the hepatic veins) in 59, and from the upper segment (from the hepatic veins to the right atrium) in 34 patients. Complete clinical, pathologic, and therapeutic data and up-to-date follow-up have been obtained through personal correspondence with several authors. All data have been examined with both univariate and multivariate analyses as predictive factors for outcome. Variables, associated with an increased risk of death from disease, included the involvement of inferior vena cava upper segment and a high-grade tumor. Patients who underwent a radical resection of the tumor (82 patients, 56.9%) had a significantly better survival (27.9% and 14.2%, 5- and 10-year survival rates, respectively). Of these patients, those with tumor of the inferior vena cava middle segment fared better than those with lower segment tumor (5- and 10-year survival rates were 48.3% and 34.4%, respectively, for middle segment tumor and 9.3% and 0.0% for lower segment tumor). Variables associated with a good outcome and longer survival were the presence of abdominal pain and the absence of a palpable abdominal mass. Despite the high rate of recurrence (52.4% of patients undergoing radical operation; median time, 25 months), radical resection of inferior vena cava leiomyosarcoma is the only chance for a long-term cure. An earlier and more accurate preoperative diagnosis, by means of modern diagnostic techniques (echography, CT scanning, magnetic resonance imaging) will allow a higher rate of radical resection to be performed with an increase in patient survival.